PTCH expression in odontogenic cysts, a cause of pathogenesis or reason for clinical complication

PTCH gene is well-known to be responsible for the development of Gorlin syndrome. It is also believed that PTCH mutation is responsible for the developmental of odontogenic keratocysts both in the Gorlin syndrome related and the sporadic cases. There is a conflict opinion in the literature regarding its role in odontogenic cysts. Furthermore, it is not known whether PTCH expression has any relevant clinical role in the outcome of the odontogenic cysts. In this study 8 odontogenic keratocysts, 16 dentigerous cysts and 23 radicular cysts treated in the academic hospital of the Free University of Brussels were subjected to an immunohistochemistry study for their expression of PTCH. The data obtained were linked to the clinical behaviour of the cysts for a follow-up of up to 20 years. Eighty eight percent of the odontogenic keratocysts (OKC), 67% of dentigerous cysts, (DC) and only 25% of radicular cysts (RC) expressed PTCH. This difference was statistically significant. Seventeen patients could be called back for clinical evaluation, the follow-up ranged from 10 to 20 years. Four patients suffering from OKC had clinical complications, 3 in the DC group and 2 in the RC group. Complications ranged from (multiple) recurrence to one case of transformation into an ameloblastoma. Only one patient suffered from clinical complication of a RC without being PTCH positive. One patient who had a PTCH negative DC and seven patients with PTCH negative RC had no clinical complications. The results indicate that PTCH expression in odontogenic cysts is more likely to be the reason of clinical complication rather than a cause of pathogenesis.